Multiple SUM in laravel (Eloquent, MySQL) - how to do it right?

Question

MySQL

It is necessary to SUM over a large number of fields, I do this

$qry = Model::where(...)-> .....
            ->addSelect($DB->raw('contractor_id, 
                sum(`credit`) as `credit`, sum(`income`) as `income`,  ......  sum(`active`) as `active`, 
            '));
        $balance = $qry->first();

Everything is good, except for one thing - numeric fields are cast as strings, which (when sent to JSON) subsequently spoils life.

I did not think of anything better than explicitly converting all values.
The question is - is there a "correct" way to get around this problem?